Abstract: With the increase of sales channels and the change of people's buying habits, fresh product sales orders tend to be small batches and high frequency. This makes joint optimization of fresh product supply chain distribution, inventory and preservation decisions become a new problem. Therefore, considering a logistic company who provides shipment service for fresh products, a stochastic model is formulated based on Stochastic Renew Reward Theory to jointly optimize the fresh investment decision and the shipment consolidation decision in this paper. And the quality corrosion characteristic of fresh products and the fresh level requirement of downstream retailers are integrated into this model. Through analyzing this model, some inherent laws is shown that how the fresh investment decision and the shipment consolidation decision impact shipment cost, penalty cost incurred by shipment consolidation and fresh-keeping cost, respectively. Moreover, the expression of the optimal fresh investment quantity per product per time is pointed out based on the given shipment consolidation quantity. Similarly, given the fresh investment policy, the expression of the optimal shipment consolidation quantity is derived. Furthermore, the equation is also shown that the optimal fresh investment decision and the shipment consolidation decision should be satisfied. Based on these analyzing conclusions, an efficient algorithm for solving the model is proposed. Finally, through conducting a lot of experiments, it is obtained that how the fresh investment decision, shipment consolidation policy and their jointly optimization save the operation cost and how the product parameters, the cost parameter sand the demand parameters effect the fresh investment decision, the shipment consolidation decision and the long-run expected average cost.All conclusions in this paper have reference significance for the enterprises in the cold chain industry to make distribution and preservation investment decisions.

Key words: logistics shipment consolidation, fresh product, freshness-keeping investment, product freshness